A rotary impact tool of this kind is provided with an impact mechanism including a hammer to be rotated by receiving a rotational force of a motor and an anvil to be rotated by receiving a rotational force of the hammer.
In the impact mechanism, when a torque equal to or greater than a specified value is applied externally to the anvil, the hammer comes off the anvil to rotate idle, and impacts the anvil in a rotation direction thereof.
Thus, according to the rotary impact tool, when fixing a screw to an object, the screw can be tightened firmly by the impact on the anvil by the hammer.
Furthermore, there is a known rotary impact tool that includes a sensor to detect an impact by the hammer and that is designed to switch the rotation speed of the motor from a normal speed to a low speed when the impact is detected by the sensor (see, for example, Patent Document 1 specified below).
According to such a technique described in Patent Document 1, it is possible to reduce an impact force caused by an impact that is to occur subsequently because the rotation speed of the motor (a driving force, in other words) is reduced when the impact is detected.
Therefore, according to the technique described in Patent Document 1, the impact force can be inhibited from being so excessive as to cause a screw head to be stripped or broken off during tightening of the screw with the rotary impact tool.